A separating device of this type is, for example, disclosed in DE 4,113,792 A1. In this known separating device, a tubular web is transported at a certain advance speed by the advancing mechanism. During this advance motion, the tubular web passes through a tearing mechanism that is arranged behind the advancing mechanism viewed in the transport direction, namely such that the rolls or cylinders of the tearing mechanism or the bands that are guided over said rollers or cylinders come in contact with the tubular web. If it is intended to separate a tubular web into tubular web sections by tearing the tubular web along a perforation that extends perpendicular to the longitudinal direction of the tubular web, the rolls or cylinders of the tearing mechanism are moved against the tubular web and driven at a higher circumferential speed than the rolls or cylinders of the advancing mechanism in order to tear off the tubular sections. During this tearing process, a tensile force is exerted upon the entire following web due to this differential speed. This tension also acts upon the advancing mechanism as long as the perforations are not separated. In the aforementioned separating device, the opposing rollers or cylinders of the advancing mechanism are arranged offset to one another. Consequently, the tubular web extends between these rollers or cylinders in the shape of a serpentine. However, practical experience has shown that the pressing force that is exerted upon the tubular web via the bands that extend around the rollers or cylinders does not suffice for retaining the tubular web once the tearing mechanism is engaged and--as described previously--exerts a tensile force upon the following tubular web. This causes an undesirable slippage that influences the tearing process unfavorably and can also lead to striations because the web slides along the bands.
DE 4,243,105 A1 discloses another separating device developed for severing perforated tube sections in which the rollers or cylinders that are arranged underneath the tubular web to be separated in the tearing mechanism as well as in the advancing mechanism are pressed against the tubular web in a synchronized fashion so as to tear off the perforated tube sections. In this case, the rollers or cylinders are respectively moved back and forth in a translational fashion, namely in a direction that extends perpendicular to the tubular web. However, the constructive realization of this separating device is comparatively complicated due to the translational guidance of the rollers or cylinders.